1. Field of the Invention
The present invention relates to a lane deviation prevention apparatus mounted on a vehicle.
2. Description of the Related Art
JP-A-2004-268845 discloses a lane deviation prevention apparatus mounted on a vehicle. According to the lane deviation prevention apparatus of the related art, a front image in front of the vehicle is photographed, a lane mark included in the front image is detected in a lane mark detection distance range, the shape of a driving lane boundary is recognized based on the lane mark, a deviation prediction judgment as to whether the vehicle deviates from the driving lane after a set deviation prediction time is made based on the shape of the driving lane boundary, and an output to prevent the deviation is outputted.
However, in the lane deviation prevention apparatus disclosed in the related art, since a position of the lane mark detection distance range for detection of the lane mark is fixed, there is a case where the deviation prediction judgment is made in a region outside the lane mark detection distance range.
In the region outside the lane mark detection distance range, since the shape of the driving lane boundary is not accurately recognized, the deviation prediction judgment becomes inaccurate, a shift occurs in the timing when the deviation prevention output is outputted, and there is a disadvantage that a reliable deviation prevention effect can not be obtained, and further, there is also a disadvantage that an uncomfortable feeling is given to a driver.
When the lane mark detection distance range is enlarged so that the deviation prediction judgment is made in the lane mark detection distance range and in the whole vehicle speed range in which the lane deviation prevention apparatus operates, it is solved that the deviation prediction judgment is made in a region outside the lane mark detection distance range. However, in this case, with the enlargement of the lane mark detection distance range, the amount of calculation of image processing becomes large, and there occurs a disadvantage that a time required for the image processing becomes long, and besides, with the enlargement of the lane mark detection distance range, cases where an image other than the lane mark is erroneously recognized as the lane mark are increased.